This invention is directed to the achievement of a plastic bundle tie which can be manufactured in endless form so that only the precise amount of tie material required for a given bundling requirement is used. The embodiment of the invention described herein is particularly intended for use in bundling wires or similiar materials but a tie device in accordance with the invention can be used under many other circumstances.
Vast numbers of bundle tie devices are used in the electrical industry for bundling wires in harnesses at the time of assembly of the harness, for bundling wires in an apparatus after the wires have been assembled to the apparatus and for other purposes. Most, if not all, of the bundle tie devices presently being used are manufactured in discrete lengths and sizes by molding processes and these commonly used ties have a head portion with an opening therein through which the other end of the tie is threaded. A detent or ratcheting device is provided between the head and the running length of the tie so that the tie can be drawn taut on the bundle. The excess tie material is usually cut off and discarded after the tie has been applied to the bundle.
While this commonly available type of bundle tie device is satisfactory in many respects, it has the undesirable characteristic of being unnecessarily expensive and wasteful. This type of tie is wasteful in that the unused or excess length of the tie must be discarded after the tie has been applied to the bundle. Furthermore, a harness maker or other manufacturer who must provide bundle tie devices on bundles of varying sizes and containing varying numbers of wires must use different sizes of ties or different lengths of ties in his operations. This requirement that different lengths of bundle ties be used is burdensome financially and logistically, and it has long been recognized that a continuous tie would be desirable.
There have been several proposals for continuous tie devices but none of these prior art devices have received widespread acceptance, particularly in the electrical industry; see, for example, U.S. Pat. Nos. 3,224,054, 3,438,095, and 3,553,793.
In accordance with the principles of the instant invention, the tie device is provided as a continuous thermoplastic strip having a generally channel shaped cross section. Spaced-apart openings are provided in the web of the strip and fine ratchet teeth are provided on the surface of the sidewalls of the web of the strip. Any desired length of the tie can be used as a complete bundle tie by merely wrapping a section of the strip around a bundle, folding one end of the strip, and passing the folded end through an opening which is adjacent to the trailing end of the strip. The web material which is between adjacent openings and the edges of the openings in the folded section defines coarse ratchet teeth and the outwardly facing fine ratchet teeth on the sidewalls provide a second ratcheting device for the tie. The folded end is pulled through the opening in the trailing end until the tie is drawn taut on the bundle. The fine ratchet teeth permit the tie to be drawn to a precise degree of tautness and the coarse ratchet teeth provide a safety feature which would prevent removal of the tie from the bundle if the holding forces of the fine ratchet teeth should be overcome. The ratchet teeth and the openings are designed in a way such that the application of the tie to the bundle is relatively simple and the holding power of the tie compares favorably with that of previously known ties having separate head portions as described above.
It is accordingly an object of the invention to provide an improved bundle tie in the form of a continuous strip which can be used in any length desired. A further object is to provide a continuous strip of bundle tie material which can be manufactured at an extremely low cost. A still further object is to provide a continuous strip of bundle tie material which lends itself to application to a bundle by means of suitable relatively simple hand tools or more complex automatic applicator tools. A further object is to provide an improved continuous strip of bundle tie material which permits fine adjustment of the tightness of the tie on a bundle and which provides, in addition, a safety or overload feature to prevent removal of the tie from the bundle.